Salting Crime Scenes with Fake DNA Becomes Possible


The New York Times is reporting a fascinating new study by researchers in Israel in which they have fooled crime scene tests with DNA they manufactured. According to the Times:

The scientists fabricated blood and saliva samples containing DNA from a person other than the donor of the blood and saliva. The researchers also showed that if they had access to a DNA profile in a database, they could construct a sample of DNA to match that profile without obtaining any tissue from that person.

"You can just engineer a crime scene," said Dan Frumkin, lead author of the paper, which has been published online by the journal Forensic Science International: Genetics. "Any biology undergraduate could perform this." …

Tania Simoncelli, science adviser to the American Civil Liberties Union, said the findings were worrisome.

"DNA is a lot easier to plant at a crime scene than fingerprints," she said. "We're creating a criminal justice system that is increasingly relying on this technology."

In the first case, the researchers amplified a small sample of DNA, the amount that might be obtained from a drinking cup or shed hair. In this case, the DNA-containing white blood cells were removed from a woman's blood and the amplified DNA from a man's hair was added to the sample which was then tested at a foresics lab.

The second technique is more worrisome. DNA forensics databases like CODIS store genetic profiles using 13 different DNA variants found in a person's genome. As the Times explains:

From a pooled sample of many people's DNA, the scientists cloned tiny DNA snippets representing the common variants at each spot, creating a library of such snippets. To prepare a DNA sample matching any profile, they just mixed the proper snippets together. They said that a library of 425 different DNA snippets would be enough to cover every conceivable profile.

Of course, if someone was trying finger a specific person with fake DNA constructed using CODIS variants, they would have to know which specific variants the target carries. Obtaining that information is currently difficult because access to DNA profiles stored in CODIS is restricted to law enforcement agencies.

Lead author Frumkin is the founder of a company, Nucleix, that offers a test that can distinguish between fake and real DNA. Real DNA is methylated; the fake DNA used in this study is not. Want to bet how long it will be before fake methylated DNA is possible?

The Times also mentions one additional concern is that celebrities might have their DNA taken from cups or hairs by genetic paparazzi. As I explained in my December 2008 column "Exposing Obama's Genome," these gene stalkers could amplify the sample and test them to find out about the celebrity's ancestry and genetic disease probabilities. I suspect that this kind of breach of privacy will become no more or less annoying than photos taken of celebrities when they dine out.